[libvirt] [PATCH] allow memballoon type of none to desactivate it

[Daniel Veillard]

  The balloon device is automatically added to qemu guests if supported,
but it may be useful to desactivate it. The simplest to not change the
existing behaviour is to allow
  <memballoon type="none"/>
as an extra option to desactivate it (it is automatically added if the
memballoon construct is missing for the domain).
The following simple patch just adds the extra option and does not
change the default behaviour but avoid creating a balloon device if
type="none" is used.

Daniel

P.S.: there is also a XEN type uspposedly for xen but I was unable to
      find any baloon code in our current xen driver so no change there


-- 
Daniel Veillard      | libxml Gnome XML XSLT toolkit  http://xmlsoft.org/
daniel at veillard.com  | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library  http://libvirt.org/
-------------- next part --------------
diff --git a/docs/schemas/domain.rng b/docs/schemas/domain.rng
index b2783b0..1e42827 100644
--- a/docs/schemas/domain.rng
+++ b/docs/schemas/domain.rng
@@ -1354,6 +1354,7 @@
         <choice>
           <value>virtio</value>
           <value>xen</value>
+          <value>none</value>
         </choice>
       </attribute>
       <optional>
diff --git a/src/conf/domain_conf.c b/src/conf/domain_conf.c
index bfe01f0..c6534b8 100644
--- a/src/conf/domain_conf.c
+++ b/src/conf/domain_conf.c
@@ -203,7 +203,8 @@ VIR_ENUM_IMPL(virDomainSoundModel, VIR_DOMAIN_SOUND_MODEL_LAST,
 
 VIR_ENUM_IMPL(virDomainMemballoonModel, VIR_DOMAIN_MEMBALLOON_MODEL_LAST,
               "virtio",
-              "xen");
+              "xen",
+              "none");
 
 VIR_ENUM_IMPL(virDomainWatchdogModel, VIR_DOMAIN_WATCHDOG_MODEL_LAST,
               "i6300esb",
diff --git a/src/conf/domain_conf.h b/src/conf/domain_conf.h
index e32188f..4361d5b 100644
--- a/src/conf/domain_conf.h
+++ b/src/conf/domain_conf.h
@@ -581,6 +581,7 @@ struct _virDomainHostdevDef {
 enum {
     VIR_DOMAIN_MEMBALLOON_MODEL_VIRTIO,
     VIR_DOMAIN_MEMBALLOON_MODEL_XEN,
+    VIR_DOMAIN_MEMBALLOON_MODEL_NONE,
 
     VIR_DOMAIN_MEMBALLOON_MODEL_LAST
 };
diff --git a/src/qemu/qemu_conf.c b/src/qemu/qemu_conf.c
index 376cd10..fb85220 100644
--- a/src/qemu/qemu_conf.c
+++ b/src/qemu/qemu_conf.c
@@ -4958,7 +4958,8 @@ int qemudBuildCommandLine(virConnectPtr conn,
      * NB: Earlier we declared that VirtIO balloon will always be in
      * slot 0x3 on bus 0x0
      */
-    if (def->memballoon) {
+    if ((def->memballoon) &&
+        (def->memballoon->model != VIR_DOMAIN_MEMBALLOON_MODEL_NONE)) {
         if (def->memballoon->model != VIR_DOMAIN_MEMBALLOON_MODEL_VIRTIO) {
             qemuReportError(VIR_ERR_CONFIG_UNSUPPORTED,
                             _("Memory balloon device type '%s' is not supported by this version of qemu"),
@@ -6575,6 +6576,9 @@ virDomainDefPtr qemuParseCommandLine(virCapsPtr caps,
         def->videos[def->nvideos++] = vid;
     }
 
+    /*
+     * having a balloon is the default, define one with type="none" to avoid it
+     */
     if (!def->memballoon) {
         virDomainMemballoonDefPtr memballoon;
         if (VIR_ALLOC(memballoon) < 0)